Polishing methods and apparatus



April 30, 1963 J. P. [DING POLISHING METHODS AND APPARATUS Filed Feb. 8. 1960 INVENTOR. JOSEPH 1? D/NG United States Patent 3,087,288 POLISHING METHODS AND APPARATUS Joseph P. Iding, 2531 N. 88th St., Wauwatosa, Wis. Filed Feb. 8, 1960, Ser. No. 7,198 9 Claims. (Cl. 51-463) This invention relates to polishing methods and apparatus, and more particularly to methods and apparatus for applying an adherent abrasive coating on the surface of a polishing member, such as a wheel or belt.

An object of the invention is to provide an improved method of applying an adherent abrasive coating on a polishing wheel or the like, wherein cement and comminuted abradant are separately sprayed onto the surface of the wheel while the wheel is in rapid motion, thus enabling effective and economical use of a quick-drying cement and producing adequate exposure of the bonded abradant on the wheel coating.

Another object is to provide an :abradant coating method wherein separate sprays of cement and abradant are commingled before they impinge on the surface of the moving polishing wheel.

Still another object is to provide a method of applying an adherent abrasive coating on the wheel wherein the spraying of the abradant is continued after cessation of the cement spray, thus enhancing the exposure of the bonded abradant.

A further object is to provide a method of applying the abrasive coating which will permit the coating to dry or set on the rapidly moving whee-l in a very short time, so that in many instances the coating application can be effected in an interval between polishing operations on successive work pieces advanced by a continuously moving carrier or conveyor.

A further object is to provide an improved apparatus for carrying out the methods of the invention.

A further object is to provide a polishing apparatus wherein the abradant coating operation is controlled by the travel of a work carrier or conveyor.

The invention further consists in the several features hereinafter described and claimed.

In the accompanying drawing,

FIG. 1 is a schematic side elevation, partly in section, of a polishing wheel apparatus of the invention for use in carrying out the methods of the invention, the view further showing control circuits associated with the apparatus;

FIG. 2 is a fragmentary transverse vertical sectional view taken generally on the line 2-2 of FIG. 1;

FIG. 3 is a fragmentary sectional plan view taken generally on the line 33 of FIG. 1;

FIG. 4 is a fragmentary bottom view of a dual spray gun assembly;

FIG. 5 is a fragmentary sectional view, taken on the same plane as FIG. 1, showing spray guns of the apparatus adjusted to provide commingling of cement and abradant sprays before the sprays reach the polishing wheel, and

FIG. 6 is a side elevation, partly in section, showing a modified form of the invention wherein the spraying apparatus is associated with a polishing belt instead of a polishing wheel.

stance a succession of spaced work pieces W are shown to be supported on a suitable carrier such as a continuously moving line conveyor 13 arranged horizontally below the wheel, the work pieces being detachably clamped to the conveyor by holders '14-. Other conventional types of work carriers may be used, such as turntables and reciprocatory carriages, or the wheel may be reciprocated ever work pieces. A suitable guard housing 15 is disposed about the wheel and has an exhaust outlet 16 which is connected to any conventional collector and abradantrecovery system, not shown.

A pair of spray guns -17 and 18 are mounted, as hereinafter described, above the wheel in adjacent circumferentially spaced relation for respectively spraying a thin coating of quick-drying liquid cement or adhesive 19 and a comminuted dry abradant 20 onto the peripheral surface of the wheel while the wheel is rotating at its nor mal high speed. The abradant spray gun 18 is spaced in the direction of wheel rotation from the cement spray gun 17, so that the cement will be deposited on the wheel in advance of the deposit of the abradant. In some instances, however, the sprays of cement and abradant may comniingle, in part or whole, before they reach the wheel, as hereinafter described. It is sometimes desirable to continue the abradant spray for a short period after termination of the cement spray, so .as to enhance the exposure of the abradant grains impinged on the cement coating applied to the wheel. In its high-speed rotation, the wheel creates :an air blast adjacent to its abrasive surface and also develops a considerable centrifugal force. The sprays of cement and abradant are delivered onto the wheel at a high velocity, so as to penetrate the air blast and to overcome the effect of the centrifugal force.

For a wheel of moderate width, the spray guns 17 and 18, which are of conventional construction per se, are mounted centrally of the width of the wheel. However, for a wider wheel provision can be made for reciprocating the spray guns across the face of the wheel, or for mounting two or more sets of guns.

Both of the spray guns 17 and 18 are preferably of the compressed air type, although in some instances the cement spray gun may be of the hydrostatic or airless injection type. The spray guns are clamped in angularly adjusted position on opposite sides of a flange bracket 21 which is adjustable along a horizontal track bar 22 extending transversely above the wheel housing parallel to the wheel axis, the track bar being supported at one or both ends on arms 23 carried by the housing, and the bracket being retained in adjusted position by a set screw 24. The spray guns are carried on respective horizontal pivot studs 25 extending parallel to the wheel axis and provided with clamping nuts 26, permitting the spray guns to be retained in vertical positions, as seen in FIG. 1, or in tilted positions, as seen in FIG. 5. Below the spray guns the top wall of the wheel housing 15 is pro- 'vided with an opening 27 to permit downward passage of the cement and abradant sprays onto the polishing Wheel.

The cement spray gun 17 is connected by a flexible hose 2% to the bottom of a closed container 29 for the fluid cement 19. Compressed air is admitted to the container above the cement level therein from a compressed air conduit 30 and branch conduit 31, the latter being provided with a reducing valve 32. Cement is thus forced by compressed air to the spray gun 17. The compressed air conduit 30 is also connected to the inlet of a normally closed solenoid-operated control valve 33, the outlet of which is connected by a flexible hose 34 to the spray gun '17 to supply the spraying air, the air pressure also controlling the usual piston-operated fluid-admission valve 35 in the spray gun. The rate of cement spray can be varied by the usual adjusting valve 36 on the spray gun 17, and also by adjustment of the reducing valve 32.

The abradant spray gun 18 is connected by a flexible hose 37 to the bottom outlet fitting 38 of an abradant container 39 from which the cornminuted abradant 2! is drawn by an aspirating action, the outlet fitting having an air admission opening 40-, and the container having a vent opening 41. A compressed air conduit 42 (which may be a part of the conduit 30) is connected to the inlet of a normally closed solenoid-operated control valve 43, and the outlet of the valve is connected by a flexible hose 44 to the abradant spray gun 18 to supply aspirating and spraying air for the abradant.

The abradant spray gun 18 includes a rotatively adjustable spray nozzle cap 45, FIG. 4, having a diametrically extending slot 46 for providing a fan-like abradant spray. The slot 46 normally extends parallel to the width of the polishing wheel, but the cap can be rotated to vary the angular disposition of the slot and thus adjust the efiective width of the abradant spray with respect to the wheel face. The abradant spray gun 18 is of a conventional type, such as that commonly used for sand blasting.

A baffle plate 47 is disposed transversely over the I polishing wheel in advance of the spray zones to reduce overspraying and to avoid clogging of the nozzle openings of the spray guns. The bafile plate extends through the housing opening 27 approximately radially of the wheel and has its inner edge spaced from the wheel face. Preferably, the baffle plate is rigidly secured to the tiltably mounted cement spray gun 17 for displacement therewith. If desired, an additional bafile plate 48 of somewhat smaller size may be similarly carried by the abradant spray gun 18 at the side thereof adjacent to the cement spray gun. The battle plate 48 projects downwardly from the abradant spray gun, and its lower edge is so disposed as not to interfere with the operation of the spray guns when they are in the tilted positions shown in FIG. 5. In some instances, a deflector plate 49 is disposed within and secured to the housing in a generally tangential position with respect to the wheel, and in the position of FIG. 1 the free edge of the deflector plate is adjacent to the lower edge of the bafile plate 47.

The liquid cement 19 is desirably of a quick-drying, silicate-base type, although other types such as resin types maybe used. By way of example, in the case of a silicatebase cement the range of silicate solutions may run from Na O:2.6SiO to Na O:3.5SiO The abradant may be of any suitable type, such as the aluminum oxide or silicon carbide type, a grit of 150 to 240 being suitable for many operations.

Renewal of the abrasive coating 12 on the polishing wheel by means of the spray guns is eifected while the wheel is running at its normal high speed. When renewal of the coating is desired, the solenoid-operated control valves 33 and 43 in the compressed air lines are energized for a short period to open position, thus admitting cement and abradant to the respective spray guns, and producing high-velocity sprays of cement and abradant onto the wheel surface, the cement firmly adhering to the wheel surface and bonding the abradant thereto. The control valve 43 for the abradant gun remains open for a short period after closing of the control valve 33 for the cement gun, thus continuing the abradant spray for a short period after cessation of cement spray, so as to insure the presence of exposed abradant grains partially embedded in the thin cement coating. The cement dries fairly quickly, for example in 8 to 12 seconds, and the polishing operation can then be resumed. When in use, the wheel may become quite hot.

It is advantageous to effect the recoating of the polishing wheel in intervals between the polishing operations on successive work pieces, so as to avoid or minimize slowing or stopping the travel of the line conveyor. For this purpose, the continuously moving line conveyor 13 is provided with suitably positioned cams 52 and 53 for periodically closing respective normally open Microswitches 54 and 55 which are connected in energizing circuits 56 and 57 for the respective solenoid-operated valves 33 and 43 controlling the operation of the spray guns 17 and 18. The energizing circuits are connected to line terminals 58. The Micro-switches are closed by the respective cams immediately after completion of the polishing operation on a work piece, and open well before the next work piece reaches its polishing position. However, the Micro-switch 55 remains closed for a short period after opening the Micro-switch 54 so as to permit spraying of abradant after cessation of spraying of cement. This may be accomplished by making the cam 52 longer than the cam 53, or by providing a delayed opening Micro-switch 55. In the case of long work pieces, such as automobile bumpers, there may be a light wheelrecoating operation after each one or two polishing operations, while for other cases the polishing wheel may operate on quite a number of successive work pieces before the wheel requires recoating or recharging. The valve control circuits 56 and 57 may also include respective disabling switches 59 and 60.

In FIG. 6, the invention is embodied in polishing apparatus including an abrasive-coated belt which is trained over a pair of pulleys or drums 71 and 72, one of which is a driver. A guard housing 75 extends over the belt, and the work carrier 13 is arranged below the belt. The housing has a top opening 77 through which cement and abradant are sprayed onto the belt from respective spray guns 17 and 18, the guns being arranged and controlled in the same manner as those in FIG. 1. A baflie assembly, like that of FIG. 1 and including plates 47, 48 and 49, is provided near the spray zones of the belt.

The application of an abrasive coating onto a polishing wheel or belt in accordance with the present invention is found to result in several advantages. By separately spraying the cement and abradant, the amount of cement required for each coating operation is substantially reduced, greatly shortening the drying time and also economizing on cement. The abradant grains adhering to the thin cement coat on the wheel or belt are eifectively exposed to the work, and this exposure can be enhanced by continuing the abradant spray after cessation of the cement spray. The drying time is reduced to such an extent that it is usually possible to eifect the abradantcoating operation between polishing operations on successive work pieces carried on a line conveyor without slowing down or stopping the conveyor. Since no abradant passes through the cement spray gun 17, there is no danger of clogging or attrition of the fluid passages of the gun. In the case of silicate-base cements the separate spraying of cement and abradant has the further advantage of allowing effective use of certain abrasive grains, such as silicon carbide, which will react with alkaline silicate solutions if they are dispersed therein.

While in each form of the invention it is preferred to employ separate spray guns for the cement and the abradant, it is possible in some cases to combine the two guns in a single structure. However, the cement and abradant would still be separately fed to the combined gun structure and would be separately sprayed therefrom so as to retain the advantages of the present invention.

If desired, the switches 59 and 60 may be normally open and manually closable to control the spraying operations, in which event the Micro-switches and their cooperating cams will form interlocks to insure proper timing and duration of the spraying operations.

It is sometimes desirable to spray a sizing coat of the cement onto the polishing member before application of the bonded abrasive coating.

I claim:

1. The method of applying an abrasive coating to the moving surface of a polishing member running at a normal high work-abrading speed and creating an air blast adjacent to said surface, which comprises projecting substantially simultaneous cooperating high-velocity sprays of an abradant-bonding fluid cement and a comminuted abradant onto said moving surface, said sprays being commingled at least in part before they reach said moving surface, and said sprays penetrating said air blast and forcibly impinging on said moving surface.

2. The method of applying an abrasive coating to the moving surface of a polishing member operating at a normal high work-abrading speed on a succession of spaced moving work pieces and creating an air blast adjacent to said surface, which comprises projecting cooperating high velocity sprays of a quick-drying abradantbonding fluid cement and a comminuted abradant onto said moving surface in an interval between polishing operations on successive work pieces, said sprays penetrating said air blast and forcibly impinging on said moving surface.

3. Polishing apparatus, comprising a polishing member having a moving surface with an abrasive coating, said polishing member running at a normal high work-abrading speed and creating an air blast at said surface, and spraying means for projecting substantially simultaneous cooperating high velocity sprays of an abradant-bonding fiuid cement and a comminuted abradant onto said moving surface to renew said abrasive coating, said sprays being directed to commingle at least in part before they reach said moving surface, and said sprays penetrating the air blast adjacent to said surface and forcibly impinging on said surface.

4. Polishing apparatus, comprising a movable polishing member having an abrasive coating, said polishing memher running at a normal high work-abrading speed, workadvancing means for bringing a succession of spaced moving work pieces into polishing engagement with said polishing member, high velocity spraying means for renewing the abrasive coating on said polishing member while said member is in motion, at a normal high workabrading speed, and means controlled by said Work-advancing means for effecting the coating operation in an interval between polishing operations on successive work pieces.

5 Polishing apparatus, comprising a polishing member having a moving surface with an abrasive coating, said polishing member running at a normal high work-abrading speed and creating an air blast at said surfaces, workadvancing means for bringing a succession of spaced moving work pieces into polishing engagement with said polishing member, means for projecting high-velocity sprays of a quick-drying abradant-bonding fluid cement and a comminuted abradant onto said polishing member while said member is in motion at its normal high Workabrading speed to renew the abrasive coating thereon, said sprays penetrating said air blast and forcibly impinging on said polishing member, and means controlled by said work-advancing means for effecting the coating operation in an interval between polishing operations on successive work pieces.

6. Polishing apparatus, comprising a polishing member having a moving surface with an abrasive coating, said polishing member running at normal a high work-abrading speed and creating an air blast adjacent to said surface, spraying means for projecting cooperating highvelocity sprays of an abradant-bonding fluid cement and a comminuted abradant onto said moving surface to renew said abrasive coating, and spra shielding baffle means extending transversely of said surface adjacent to the spray-impinging region thereof and in advance of said region.

7. Polishing apparatus, comprising a polishing member having a moving surface with an abrasive coating, said polishing member moving at a normal high work-abrading speed and creating an air blast adjacent to said surface, spraying means for projecting cooperating highvelocity sprays of an abradant-bonding fluid cement and a comminuted abradant onto said surface to renew said abrasive coating, and baffle means including an air-blastintercepting bafile wall extending transversely of said moving surface in advance of the region of said sprays.

8. In a polishing apparatus, a polishing member having a moving surface with an abrasive coating, said polishing member moving at a normal high work-abrading speed and creating an air blast adjacent to said surface, and a pair of first and second spray guns disposed in adjacent relation and operable to direct respective high-velocity sprays of an abradant-bonding fluid cement and a comminuted abradant through said air blast and against said moving surface, said spray guns being relatively angularly adjustable to vary the relative position of the sprays issuing therefrom.

9. Polishing apparatus, comprising a polishing member having a moving surface with an abrasive coating, said polishing member moving at a normal high work-abrading speed and creating an air blast adjacent to said surface, spraying means for projecting cooperating highvelocity sprays of an abradant-bonding fluid cement and a comminuted abradant through said air blast and onto said moving surface to renew said abrasive coating, and spray-shielding bafiie means etxending transversely of said moving surface in spaced relation thereto and in advance of the region of the sprays and carried by said spraying means.

References Cited in the file of this patent UNITED STATES PATENTS 1,624,290 Taylor et al. Apr. 27, 1927 2,083,773 Burroughs June 15, 1937 2,332,992 Davis Oct. 26, 1943 2,404,207 Ball July 16, 1946 2,471,727 Creamer May 31, 1949 2,554,079 Wilson May 22, 1951 2,590,697 Grove Mar. 25, 1952 2,712,987 Storrs et al. July 12, 1955 2,793,478 Rohowetz May 28, 1957 2,923,108 Kirkman et al. Feb. 2, 1960 2,940,228 Helling et al. June 14, 1960 FOREIGN PATENTS 330,322 Great Britain June 12, 1930 

9. POLISHING APPARATUS, COMPRISING A POLISHING MEMBER HAVING A MOVING SURFACE WITH AN ABRASIVE COATING, SAID POLISHING MEMBER MOVING AT A NORMAL HIGH WORK-ABRADING SPEED AND CREATING AN AIR BLAST ADJACENT TO SAID SURFACE, SPRAYING MEANS FOR PROJECTING COOPERATING HIGHVELOCITY SPRAYS OF AN ABRADANT-BONDING FLUID CEMENT AND A COMMINUTED ABRADANT THROUGH SAID AIR BLAST AND ONTO SAID MOVING SURFACE TO RENEW SAID ABRASIVE COATING, AND SPRAY-SHIELDING BAFFLE MEANS EXTENDING TRANSVERSELY OF SAID MOVING SURFACE IN SPACED RELATION THERETO AND IN ADVANCE OF THE REGION OF THE SPRAYS AND CARRIED BY SAID SPRAYING MEANS. 